This invention relates generally to fuse holders and more particularly to fuse clips incorporating means for preventing insertion of improper fuses.
Fuse clips of the conventional type which include flexible clamping arms for receiving the end terminals of cartridge fuses have the inherent disadvantage of being susceptible to the insertion of fuses having current-interrupting capacities different from the preferred fuse. With a view toward correcting this possibly dangerous situation, some prior fuse clips have been provided with rejection features in the form of interference means for resisting an insertion of such improper fuses. However, the interference means have been formed in the flexible clamping arms of the fuse clip, and the arms, while resisting the insertion of an improper fuse, were susceptible to being overstressed during attempted insertion. Moreover, in some cases, fuse clips which included interference means incorporated within flexible clamping arms could have improper fuses inserted therein, provided sufficient pressure was exerted on the fuse. Therefore, what was needed was an improved rejection means which would resist the insertion of an improper fuse.
Additionally, from an economical standpoint, it is undesirable to manufacture two separate fuse clips; one for fuses having annular grooves therein, and one for fuses without such annular grooves. The interruption of production runs for changeover, and the necessity for adequate inventories, result in unwanted expense for a relatively inexpensive item. Another uneconomical practice resulting from the use of two distinct fuse holders is the requirement that the desired alignment of fuses be known prior to shipment of the assembly of, for example, fuse boxes. This results in additional expense during the fabrication of such items. Therefore, the most desirable practice would be to provide a basic clip which can be utilized with either type fuse, and which can be modified at the point of installation, in the field, by simple and inexpensive means.
One method utilized in the prior art to accomplish these objectives is illustrated in U.S. Pat. No. 2,943,295, issued June 28, 1960. This method utilized openings in the clamping arms of the main fuse clip body, and inserting an interference member between the two clamping arms and extending outwardly beyond them through the openings. This interference member could then be crimped or otherwise secured to the fuse clip body, and would prevent the insertion of improper fuses. However, this invention has its drawbacks in that it is generally necessary to replace the fuse clip in the field, and the field installation is complicated. Another method utilized in the prior art is the use of a retaining clip which fits into the molded casing upon which the fuse clip rests. The retaining clip has an extension which extends into the main fuse clip body between the clamping arms, and prevents the insertion of improper fuses. However, this device has disadvantages in that it can only be utilized in those installations where the molded casing has provisions made therein for the insertion of the retaining clip.